In U.S. Pat. No. 4,257,002 and commonly-assigned herewith, an electrical continuity tester is described of type generally addressed by the subject application. Such tester is adapted for receiving a known-good multiconductor harness and has microprocessor capabilities for examining the known-good harness and for storing electrical continuity characteristics thereof, such as continuity existing between the terminals of connectors on opposite ends of the cable. The tester further includes the capability for accepting input data from a recording medium, such as a tape cassette, which stored information may identify the electrical continuity characteristics of a harness.
Among the component parts of the referenced continuity tester are a console panel having a mode select switch, by which one may direct operation of the tester in the various modes, a microprocessing unit (MPU), a read only memory (ROM), which fixedly stores the instructions under which the tester operates, a random access memory (RAM), which stores the information either derived from the known-good harness or cassette tape and a scanning unit which examines the electrical characteristics of harnesses connected to the tester for evaluation and correspondence with the stored infomation. Display circuitry provides indication to the user of the tester of various sorts, inclusive of an identification of electrical continuity characteristics of the test cable which are in disagreement with the corresponding stored characteristics.
While the referenced tester fully meets the needs of cable harness evaluation wherein the confirmation of "shorts" and "opens" is sufficient, various applications arise in which more expansive test capability is needed. For example, where harnesses are for automotive use and terminate in circuitry having resistors, diodes, lamps and the like and where testing is desired of both the cables and the connected circuitry, the referenced tester falls short of the test requirements. While one can segregate the test procedure to obtain the benefits of the referenced automated tester for cable continuity evaluation, the supplemental circuitry testing would be performed at vastly slower rates through additional test equipment not coordinated with the referenced tester under common microprocessor control.